Apparatus and method for making connector bolts



Oct. 30, 1951 J. PAVELKA' 2,573,213

APPARATUS AND METHOD FOR MAKING CONNECTOR BOLTS I Filed Oct. 6; 1944 3 Sheets-Sheet l INVENTOR- J EPZ PAVELKA AT RNEY at w, 395% J. PAVELKA 9 9 I APPARATUS AND METHOD FOR MAKING CONNECTOR BOLTS Filed 051 s, 1944 5 Sheets-Sheet 2 f 5 W M v FIGA.

NVENTO H PAV KA AT GREY" at 361 WEE J. PAVELKA APPARATUS AND METHOD FOR MAKING CONNECTOR BOLTS Filed Oct. 6, 1944 3- Sheets-Sheer, 3

Patented Oct. 30, 1951 UNITED STATES PATENT 2,573,218 OFFICE APPARATUS AND METHOD FOR MAIHNG CONNECTOR BOLTS 6 Claims.

The invention relates to the manufacture of U-shaped connector bolts such as are provided with a nut and are commonly used for clamping together separate electrical conduit wires or cables. The invention comprises a 'novel apparatus formaking the bolt and a novel method followed in the making of the bolt in connection with the use of the apparatus.

One object of the invention is to form the bolt from rolled bar stock without waste.

Another object is to forge the stock so that relatively inexpensive material may be used, and an associated object is to avoid elongating thr material in the forming of the bolt and thus decreasin the strength of the material.

Another object is to manufacture the connector bolt from .bar stock without the usual manual handling of the individual blanks between the cutting of the same from the stock and the completion of the manufacture of the bolt, thus expediting the manufacture of the bolt and avoiding likelihood of injury to operators in the feeding of individual blanks. to the mechanism.

These and other detail objects of the invention, as will appear from the following description, are attained by the machine and method described below, reference being had to the accompanying drawings, in which- Figure 1 is a perspective of a die unit which is to be mounted on the bed of a power press (not shown) of usual construction having a head which mounts parts associated with the parts of the die unit and indicated in detail in other figures.

Figure 2 is a detail cross section through a part of the forging device of the die and the associated punch part and is taken approximately on the line 2-2 of Figure 1.

Figure 3 is a section taken at right angles to Figure 2 on the line 3-3 of the latter.

Figure 4 is a section and elevation taken approximately on the line 4-4 of Figure 1 and showing the cutting on or severing device and the forming die.

Figure 5 is a vertical transverse section taken on the line 5-5 of Figure 4 at the beginnin of a downward movement of the press head.

Figure 6 is a detail vertical section taken on the line 6-45 of Figure 4 and showing the parts in the position assumed after the press head has moved downwardly from the position shown in Figure 5.

Figure 6a is a similar position showing the parts in the position assumed after further downward movement of the press head.

Figure 7 is a detail section corresponding to the left hand end of Figure 4 but showing the forming punch cooperating with the forming die. The full .line position indicated is assumed after further downward movement of the press head from the position shown in Figure 6a and indicating the lowermost position of the punch.

Figure B is a sectioncorresponding to Figure 7 but showing the parts in the position assumed '2 as the press head rises from the position shown in Figure '7 to its highest position.

Figure 9 is a top view of the transfer device associated with the die unit by which the 'U- shaped pressing formed during the operation shown in Figure 7 is removed from the position shown in Figure 8 and fed to the threadingdies as shown in Figures 1 and 11.

Figure 10 is a detail section taken on the line l0-l0 of Figure 9 and showing in full lines the U-shaped pressing and the fingers gripping the same in the position indicated in Figure "9 and showing in broken lines an ensuing position of these parts.

Figure 11 is a detail section taken on the line I l-l l of Figure 1 and shows the parts indicated in Figure 10 when moved toan ensuingposition just prior to the formation of the threads on the legs of the pressing.

Figure 12 corresponds to Figure 11 but shows the parts in the position assumed at the completion of the threading operation.

Figure 13 is a detail side view of a portion of the transfer device looking in the direction indicated by the arrows l3l3 in Figure 9 and showing associatedpress head parts.

Figure 14jis a detail view showing a press head part in bolt releasing position.

Figure 15 is a perspective of the blank severed from the stock just prior to the operation indicated in Figure 7 in which the blank is pressed intoa U-shape.

Figure 16 is a perspective of the U-shaped pressing following the operation indicated in Figure 7.

Figure 17 is a perspective of the completed bolt following the operation indicated in Figure 12. V

The machine parts will be described in the order of their successive operations in forming a complete bolt, but it will be understood some of the operations are simultaneous on different pieces of work which are passing through the machine at one time.

The base plate I of the die unit will be fixedly mounted on the bed (not shown) of a power press. Flat bar stock 2 will be fed by any suitable punch press automatic stock feeding means in a left hand direction to the right hand end of the unitthrough a guide member 3 to a swagelike anvil l (Figures 2 and 3.). A swage-like hammer 5 mounted on the press head H cooperates with anvil 4 to forge the flat bar to provide spaced portions of a rounded cross section, as indicated at B, and an intermediate portion 1 substantially unchanged in cross section contour and area, although preferably somewhat thicker than the bar stock.

From the swaging anvil the stock slides into and through a suitable passageway in an elongated box 8 (Figure 4) havin axially aligned trunnions 9 at its opposite ends journaled in plate I directly beneath the passageway. A shear blade I9 is fixed on plate I and a cooperating blade H is fixed on box 8. These blades have work-receiving slots Illa and Ha normally aligned-with each other and with the passageway in the box.

Struts l2 and 13 (Figure 5). are loosely pivoted at 14a to the sides of a channel l4 mounted on press head H. Springs 15 thrust struts l2 and 13 toward each other but such movement is limited by studs 12a and 13a whoseheads engage fixed cams 16 on plate I. Strut I2 is a little longer than strut l3. Projections l1 and It! on opposite sides of box 8 are directly beneath the lower ends of struts l2 and 13 respectively when the press head is in its uppermost position, .but as the press head descends, strut l2 strikes projection-.11, rocking box 8 in an anticlockwise direction on trunnions 9, as indicated in Figure 6, forcing the left hand side of slot [9a, in blade .10, and the right hand side of slot Ila, in blade I l, into the stock. Further downward movement .ofwthe press head results in stud 12a engaging .cam 16 and pulling strut l2 off of projection 11 .and this is followed by engagement of the lower end of strut l3 with projection I6, whereupon box 8 is rocked in the opposite direction (Figure 6a), forcing the right hand side of slot a .and the left hand side of slot Ila into the stock. By shaping the upper ends of struts l2 and 13, as shown in Figure 5, and by providing a loose fit for pivot pins Me, the upper ends of the struts may directly engage the bottom of channel 14, thus relieving the pivot pins of forces tending to shearthem. The successive rockings of box 8 so a to force thestock against opposite sides of theslots results in the severing of an individual blank B with clean cut ends free of fins or burrs such as are produced by the usual shearing operation in the formation of connector bolts.

When the blank is severed, it drops from the broken line position, to .the full line position shown in Figure 4 where the ends of its round portionsrest upon flat surfaces 19 (Figure 7) and its intermediate portion spans the well 29 in the plate (Figure 4). Up to this moment, the widest dimension of the stock has been upright (to facilitate the swaging operation), but when the stock is freed of upport from the sides of its passage- .Way-in box. 8 and rests upon its trunnion-like ends it is no longer stable and its greatest width tends to depart from the vertical and the blank assumes the angular position about as indicated at B in Figure 6a. While in this position, a punch 2| (Figure 7) mounted on the press head descends, first turning the greatest width of the blank B to a full horizontal position and then bending the blank into the U-shaped pressing shown at P (Figure 16). Figure 7 shows the position of the parts at the end of the downward movement of the press head. As the head moves upwardly from the position shown in Figure '1, a plunger 22 elevates pressing P to the position shown in Figure 8. Plunger 22 is actuated by a horizontal bar 2311 carried by vertical rods 23 attached to the press head and descending through openings therefor in plate I.

Pressing P is then removed from the forming punch and die by a transfer device including a plier-like gripper with jaws 24 and arms 26 (Figures 1 and 9) which are pivoted upon a pin 25 which slides transversely of a plunger 21 (Figure 1) which slides longitudinally of a sleeve 28 on plate I. The outer end of plunger 21 is connected to an arm 29a on a slide 29 received in a guide 30 parallel to sleeve 28. A spring 3| thrusts slide 29 and plunger 21 in the direction of the arrow A. Toggle links 32 and 33 (Figures 1 and 13), connected by a pivot pin 34, have their outer ends pivotally connected to slide 29 and plate 1 respectively. A roller 35 on pin 34 is engageable by a descending clip 36 (Figure 13) on press head H as the latter descend to spread the outer ends of the toggle links and moves plunger 21 and gripper 24, 26 in the direction opposite to arrow A. A pin 31 on plunger 21 slides in a cam slot 38 in sleeve 28 and, after initial straight line movement opposite to direction of the arrow A, the plunger and gripper are rotated 90 about the plunger axis from the position shown in solid lines to the position shown in broken line in Figure 10.

In this position, pressing P is axially aligned with an anvil 39 (Figure 11) projecting from a block 49 yieldingly supported between guides 4| (Figure 1) by coil springs 42. Pin 25 and gripper 24, 26 are moved to the right, so that the legs of pressing P straddles anvil 39, by a slide 43 (Figure 1) received in a guide 44 and having a cam face 45 engageable by a descending clip (not shown) on the press head corresponding generally to clip 35 so that slide 43 abuts the left hand end of pin 25. As pin 25 moves to the right, a stud 46 engages a stationary cam 41, and these element serve as a safety device to insure the full 90 rotation of plunger 21. Threading dies 48 and 49 (Figure 11) are mounted on plate I and presser head H respectively below and above anvil 39 and receive the legs of pressing P between them as the pressing legs straddle anvil 39. Following this positioning of the pressing, dies 48 and 49 are moved towards each other to impress or stamp the threads T (Figure 1'1) on the legs of the pressing and, at the same time, to flatten the inner surfaces F of these legs, thus completing the formation of the connector bolt.

When the press head rises, a spring 59 (Figure 1) returns slide 43 to its left hand position shown in broken lines in Figure l and, at the same time, a spring 5| returns pin 25 and gripper 24, 26 to theirleft hand positions, withdrawing the completed bolt from the threading dies and anvil.

, The gripper is then caused to release and drop the bolt by the rotation of a shaft 52 journalled in a block 53 on plate I. A bar 54 (Figure 14), attached to the press head and slidable vertically in an opening 55 (Figure l) in block 53, has a recess 56 receiving a stud 51 on shaft 52. As the press head rises from its lowermost position, permitting slide 43 and gripper 24, 26 to move to the left, the lower arm 26 of the gripper moves beneath the flattened right hand end of shaft 52. Further upward movement of the press head and bar 54 results in the lug at the lower end of recess 56' engaging pin 51 to rotate shaft 52 in a clockwise direction, as indicated by the broken lines in Figure 14, and the flattened end of the shaft moves the gripper arm downwarly so as to release the completed bolt and it drops through a suitable opening in plate I to a receptacle. Spring 3|, pin 31 and cam 38 then cooperate to rotate gripper 24, 26 to the horizontal position (Figure 9). Subsequent lowering of bar 54 releases pin 51 from the lug at the lower end of recess 56 and shaft 52 is returned to the normal position shown in Figure l by engagement of its arm 68 by a spring 69 seated in a recess in block 53.

It is desirable that the last portion of the movement of plunger and gripper 24, 26 towards the newly formed pressing P be a quick movement so that the partly open jaws of the gripper,

accepts strildng the diverging edges of the, head of the pressing, willspread to receive the head of the pressing between them. To obtain such action, clipifi (Figure. 13) is provided with -a trigger 6.0 pivoted at 61 and yieldinglyheld against apin 62 by a spring E53. When the press head descends, roller-35 travels towards the left along the bottom of clip 36 (successive positions of the roller :being indicated at 35a and 35b) and trigger .60 swings to accommodate this movement. When the press head rises, the relative :movement of the'roller is downwardly and to the right. until it reaches the position indicated :at .35cwhen trigger 60 halts further movement :of the roller and of the toggle links 32, 33 and the movement "of plunger 27 and the gripper in the direction of arrow A. However, as the press head nears the end of its upper movement, rolier 35 wiil rideover the lower end of trigger 60 and spring 3:! may iunction to snap plunger 21 and gripper 24, 26 to the position indicated in Figue 9. During such movement, the rear edge of the pressing head abuts a stop ill (Figures 8 and 9) resisting the movement of the head under the thrust-of spring 31 and the gripper.

As previously indicated, different operations described above occur at substantially the same time on different pieces of work. A cycle of operations beginning with the press head in its highest position would be as follows: Durng the first portion of the'downward movement of the'press head, clip 36 actuates toggle 32, 33 and gripper 24, 26 to remove the previously formed pressing P from beneath punch 2|. As the head continues to move downwardly, the punch press automatic stock feeder arrangement (not shown) causes the stock '2 to be fed to the left so as to project its inner end over the die well 20, and this is followed by the swaging of the flat bar, as indicated in Figures 2 and 3. At the same time, the previously swaged forward end of the bar is cut off or severed to form the blank B, as indicated in Figures 4, 5, 6 and 6a. At the same time, the gripper transfers the previously formed pressing P to the threading dies 48, 69 (Figure 11). Subsequent downward movemerit causes punch 2| to descend into well 20 forming the pressing P. At the same time, threading dies 48, 49 andanvil 39 cooperate to flatten the inner faces of the legs of the pressing and to impress the threads on the outer laces of the legs.

Subsequently the press head moves upwardly and the first action is the separation ofthe threading dies followed by the movement of gripper 24, 25 and the completedbolt from. anvil 39. Then bar 54 rotates shaft 52 to releasethe :bolt. Then gripper 2t, 26 is rotated to the horizontal position but is restrained against movement towards the newly formed pressing by trigger 611 (Figure 13). At this time plunger 22 is raised and, at the end of its upward movement, toggle roller .35 is released from trigger 60 and gripper 24, 26. jumps to the position shown in Figure 9, its jaws spreading as they strike the head of pressing P and gripping the latter. It will be understood that the jaws are forced together by a spring 65 (Figure 9) and opening movement of the jaws is limited by a bar 66 havinga slot at one end receiving the screw 61 by which the bar is attached to the gripper arm.

In making a connector bolt as described: above, the; bar's-took is fed into the machine and the completed bolt is discharged from the" machine without any-intermediate manual handling of individual blanks. or pieces of work. This in .itself makes it possible to manufacture the bolt more speedily and otherwise more economically than has been done previously when successive operations upon the work are performed in separate machines. This complete manufacture in a single machine .is facilitated by elimination of the usual process of drawing out the legs of the bolt and trimming rough edges and surplus material from the ends of the legs prior to the threading operation.

It is to be'understood that the forming operation indicated in Figure 7 is a bending operation and the legs are not stretched or drawn out so as to produce irregular lengths or uneven ends. The square shoulders 210. on the punch (Figure 8 contribute to the maintenance of square ends on the pressing. The only elongation of the metal resulting from this forming operation is such as takes place as the legs are bent at right angles to the head. As the result of the swaging operation, the of the stock material are compressed and the strength of the material is greater than that of the bar stock and the finished product is thus distinguished from products made in the usual manner in which fibers of the stock material are stretched and otherwise distorted during manufacture. As the result, softer and less expensive stock material may be used.

It will be understood that the stock mater-iai need not necessarily possess the cross sectional contour indicated but that other forms of bar stock may be used and the term bar is not here used as of rectangular cross section.

The details of the mechanism may be varied substantiall without departing from the spirit of the invention, and the exclusive use of those modifications coming within the scope of the claims is contemplated.

What is claimed is:

1. The method of makinga connector bolt from bar stock of rectangular cross section which is characterized by simultaneously swaging the bar to form spaced portions of round cross section of greater diameter than the thickness of the bar stock and an intermediate portionof flattened sections of greater thickness than the thickness of the bar stock and subsequently severin the said swaged portions from the bar to form an individual blank and then bending the blank to form a head of the flat section with round legs projecting therefrom at right angles to the hat face of the head;

2. In a machine for makin a U-shaped connector bolt with threaded legs, a substantially horizontal bed plate with a forming die fixed thereon, a vertically reciprocating press head with a punch cooperating with said die to bend a straight blank into .a U-shaped pressing with its legs disposed vertically, a vertically reciprocating member normally below said die for expelling the pressing from the die, a grippin structure reciprocally mounted on said bed plate to move to.- wards and engage the intermediate portion of the expelled pressing and to. retract it from. the die and punch said structure alsobeing rotatable on saidbed to rotate the pressing to position its legs horizontally, and means mounted on the bed plate and actuated by the press head for impressing threads in the pressin legs after they have been turned to horizontal position.

3. In a machine for making connector bolts from elongated rectangular section bar stock having a greater width than thickness, a guide mom-'- her with upright sides spaced apart corresponding to the thickness of the bar to form a passage for holding the bar upon one of its edges, pairs of opposing swaging elements adjacent one end of said member, said pairs being spaced apart longitudinally of the longitudinal axis of said passage and the elements of each pair being movable relative to each other transversely of said axis, said elements having opposing faces of arcuate cross section for swaging spaced portions of the bar to form said portions into substantially round cross section while leaving an intermediate portion corresponding to the initial rectangular section, shear blades adjacent the other end of said member movable relative thereto transversely of said axis for severing a unit from the bar as it is projected from said passage, said blades being positioned longitudinally of said member relative to said swaging elements so as to cut through successive rounded portions of the bar, a die adjacent the latter mentioned end of said member and having an open top well which may be spanned by one of such units comprising rounded end portions and an intermediate fiat portion, said die having horizontal flat surfaces at opposite sides of the upper end of said well for supporting the end portions of such a severed bar unit and accommodating the partial rotation of theunit to a position with its flattened cross section portion inclined from the vertical, and a vertically movable punch over said die well for descending on said flattened cross section portion and into said well to form a U-shaped pressing.

4. In a machine for makin connector bolts from elongated bar stock, a die having a work receiving passage, a relatively movable punch aligned with said passage for engaging a straight blank lying across the die opening and thrusting it into the die to form a U-shaped pressing, a reciprocating plunger entering the die from the side opposite to said punch to expel the pressing from the die, an elongated carrier spaced horizontally from the top of said die, means mounting said carrier to provide it with reciprocal axial movement between an advanced position and a retracted position, to have 90 oscillating movement about its axis as it is reciprocated between said advanced and retracted positions and to have back and forth movement transversely of its axis between a projected position and a withdrawn position, a plier-like structure carried by the end of said carrier nearest said die and comprising a pair of jaws and a pivot pin therefor extending transversely of the carrier axis, said pin being disposed vertically when the carrier is in said advanced position and horizontally when said carrier is in others of said positions, a pair of coacting thread pressing dies and anvil adjacent to said jaws when said carrier is shifted to said projected position, and means for moving said dies towards said anvil when said plier jaws are in said projected position.

5. In a machine for making connector bolts, a punch and die member movable vertically relative to each other to form a straight blank into a U-shaped pressing having a cross bar and parallel legs, means insertable in the die from the side opposite the punch for expelling the U-shaped pressing from the die, an anvil and coacting thread pressing device spaced laterally from said forming die, a plier like structure with spring pressed jaws mounted on a carrier between said forming die and said anvil and pressing device,

means automatically moving said carrier to advance said structure towards said forming die as the punch moves away from the forming die and to position said jaws over the die to grip the cross bar end of the pressing as it is expelled from the forming die, a device cooperating with said means as it moves said structure and pressing away from said forming die to rotate said structure to turn said pressing horizontal, and means to move said structure and pressing transversely of the first mentioned straight line movement to insert the spaced legs of the pressing between said anvil and threading device.

6. In a machine for making a U-shaped connector bolt with threaded legs, a bed plate with a forming die fixed thereon, a vertically reciprocating press head with a punch cooperating with said die to bend a straight blank thereon into a U- shaped pressing with its legs disposed vertically, a gripping structure slidably and rotatably mounted on said bed plate to move horizontally over said die and engage the intermediate portion of the pressing and to move away from the die with the pressing, all while the punch is raised above the die and to then rotate 90 about a horizontal axis to position the pressing legs horizontally, an anvil mounted on the bed plate parallel to and above the same and adapted to be received between the legs of the pressing, means moving the gripping structure towards said anvil, after the gripping structure has been rotated as described to position the pressing over the anvil, and c0- acting threading dies actuated towards each other by the subsequent movement of the press head relative to the bed plate after the pressing has been placed on the anvil to impress threads on the outer face of the pressing legs.

' JOSEPH PAVELKA.

REFERENCES CITED The following references are of record in the file of this patent:

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